Ergonomic handle and articulating laparoscopic tool

ABSTRACT

The present invention relates to a laparoscopic apparatus. The apparatus comprises a handle having a body portion, a top surface, opposite bottom surface, a proximal and distal end. The top surface of the base is contoured to compliment the natural curve of the palm. The apparatus further includes a shaft projecting from the distal end of the handle. The shaft has a proximal and distal end. A control sphere is located on the handle. The control sphere can be moved by one or more of a user&#39;s fingers to indicate direction. An end effector is located at the distal end of the shaft. The end effector is connected to the control sphere such that movements made to the control sphere control cause movement (articulation) of the end effector.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. §120 toU.S. application Ser. No. 11/056,021 filed Feb. 11, 2005, which claimsthe benefit of priority to U.S. Provisional Application No. 60/544,286filed on Feb. 12, 2004, both of which are hereby incorporated byreference in their entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

BACKGROUND

Surgeons have identified and studies have shown, laparoscopic techniquesrequire greater concentration and place greater mental and physicalstress on surgeons than open surgery. The tools that laparoscopicsurgeons must use are difficult to use and because of suboptimal design,they may actually be doing harm to the highly trained physician.Additionally, poor laparoscopic tools increase physician fatigue,creating potential for errors that may harm the patient.

Specialized instruments are required for laparoscopic surgery due to thesmall ports. The design of these instruments is critical to the resultof the surgery. Current laparoscopic instruments have been found to bevery poorly designed ergonomically and it is likely that ergonomics werenot considered at all. Some practicing laparoscopic surgeons frequentlyexperience post operation pain or numbness. This is generallyattributable to pressure points on the laparoscopic tool handle.Furthermore, four different handle designs used on laparoscopic tools(shank, pistol, axial, and ring handle) have been found to result ineither painful pressure spots or caused extreme ulnar deviation.

Compared to general surgery, laparoscopic surgery is a new practice.Therefore, the tools available to perform the procedures are not yetperfected. Limited work has been done by others to improve both thetools and procedures used in laparoscopy; however, an optimized tool,based on task analysis of laparoscopic surgery and sound ergonomicprinciples has not been prototyped and tested fully to date.

Furthermore, non-ergonomic tool handles often cause pain and discomfortand also result in painful pressure spots. It would be beneficial tohave a laparoscopic tool with an ergonomic handle, an intuitivehand/tool interface, such as a control sphere, and an articulating endeffector. It would also be beneficial to have an ergonomic tool handlewith an intuitive hand/tool interface for use with other types of tools.

SUMMARY

In one embodiment, the present invention relates to a laparoscopicapparatus. The apparatus comprises a handle having a body portion, a topsurface, opposite bottom surface, a proximal and distal end and a shaftprojecting from the distal end of the handle, the shaft having aproximal and distal end. The apparatus further comprises a controlsphere located on the handle and an end effector located at the distalend of the shaft, wherein the end effector is connected to the controlsphere such that movements made to the control sphere control movementof the end effector.

In another embodiment, the present invention relates to an ergonomichandle apparatus for use with a tool. The handle apparatus comprises abase having a body portion, a top surface, opposite bottom surface, aproximal and a distal end, where the top surface of the base beingcontoured to compliment the natural curve of the palm. The handleapparatus further comprises a control sphere located on the base,wherein the control sphere can be moved by one or more of a user'sfingers to indicate direction and at least one lever projecting from thebottom surface, wherein the lever may be actuated by a user.

In yet another embodiment, the present invention relates to alaparoscopic apparatus. The apparatus comprises a handle having a bodyportion, a top surface, opposite bottom surface, a proximal and distalend, where the top surface of the base is contoured to compliment thenatural curve of the palm. The apparatus further includes a shaftprojecting from the distal end of the handle, the shaft having aproximal and distal end and a control sphere located on the handle. Thecontrol sphere can be moved by one or more of a user's fingers toindicate direction. An end effector is located at the distal end of theshaft and the end effector is connected to the control sphere such thatmovements made to the control sphere control movement of the endeffector.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a laparoscopic apparatus in accordancewith an embodiment of the present invention;

FIG. 2 is a side perspective view of an ergonomic handle in the closedposition in accordance with an embodiment of the present invention;

FIG. 3 is a side perspective view of an ergonomic handle in the openposition in accordance with an embodiment of the present invention;

FIG. 4 is a longitudinal cross sectional view of an ergonomic handlewith a slip lock in accordance with an embodiment of the presentinvention;

FIG. 5 is an enlarged side perspective view of an ergonomic handle inaccordance with an embodiment of the present invention;

FIG. 6 is an enlarged perspective view of a portion of a laparoscopicapparatus in accordance with an embodiment of the present invention;

FIG. 7 is top perspective view of a control sphere of an ergonomichandle in accordance with an embodiment of the present invention;

FIG. 8 an enlarged perspective view of graspers of a laparoscopicapparatus in accordance with an embodiment of the present invention;

FIG. 9 is a perspective view of an ergonomic handle used with alaparoscopic apparatus displaying the internal components in accordancewith an embodiment of the present invention;

FIG. 10 is side perspective view of a laparoscopic apparatus with acutaway showing the internal control cables in accordance with anembodiment of the present invention;

FIG. 11 is a view of a reverse use position of a laparoscopic apparatusin accordance with an embodiment of the present invention;

FIG. 12 is an exploded perspective view of an end effector and graspersof a laparoscopic apparatus in accordance with an embodiment of thepresent invention;

FIG. 13 is a side perspective view of an internal portion of theergonomic handle in accordance with an embodiment of the presentinvention; and

FIG. 14 is a side perspective view of the internal portion of a lefthalf of an ergonomic handle in accordance with an embodiment of thepresent invention.

DETAILED DESCRIPTION

With reference to FIG. 1, an ergonomic laparoscopic tool (10) is shown.Laparoscopic tool (10) comprises of five main components: an ergonomichandle (12), several controls, a shaft (14), an articulating endeffector (16), and graspers (18). The graspers (18) may be any effectorssuch as cutting forceps and jawed end effectors or may be powered forcauterizing. The cauterizing may include electrosurgical cutting andcoagulation of tissue.

In one embodiment, the shaft (14) is a 10 mm shaft. In this embodiment,the shaft is about 10 mm in diameter and about 40 cm long. The shafthouses the wire guides and actuation cables, described later. However,one of skill in the art will appreciate that the shaft, wire guides andactuation cables are scalable and may be any size, including, but notlimited to, about 3 mm and about 5 mm in diameter and about 35-55 cmlong.

With reference next to FIG. 2, the tool handle (12) is a smooth,contoured shape. It is designed ergonomically for comfort and usability.In one embodiment, the handle (12) is about 155 mm (length) by about 35mm (height) by about 45 mm (width). In another embodiment, the handle(12) may be about 150-165 mm in length, about 30-40 mm in height andabout 40-50 mm in width. The handle has a top and bottom surface and aproximal and distal end. The proximal end of the handle is locatednearest a user and the distal end is the end located farthest from auser. The top surface of the handle is contoured to compliment thenatural curve of the palm.

In one embodiment, the handle circumference is about 5 cm and tapered inshape. A preferred range of handle circumference is from about 4 cm to6.5 cm. The distal end of the handle is also curved such that the toolshaft (14) is angled at about 135 degrees to increase the accuracy ofpointing with the tool. However, the distal end of the handle may becurved to at any variety of angles depending on the tool that the handleis used with. The handle is designed to fit hand sizes ranging fromabout the 5th percentile female to about the 95th percentile male. Thetool handle is described in relation to a laparoscopic instrument,however, it will be appreciated that the ergonomic tool handle (12) maybe used with any variety of tools including a homeland security device,such as a sensing device, or a laser pointer for presentations.

The handle (12) is designed for comfortable use with three differenthand orientations. The first hand position is such that the thumbcontrols the sphere, and the fingers are wrapped around the handle andsqueeze the grip (20). The second hand position uses the thumb tosqueeze the grip (20), and the fingers are wrapped across the top of thehandle (12) with the index finger controlling the sphere (26). The thirdis a reverse grip shown in FIG. 11. In the reverse position, the fingersare wrapped around the handle (12) so that the index finger squeezes thegrip (20), the control sphere (26) is moved with the user's thumb andthe collet mechanism (24) is controlled with the user's pinky finger.The collet mechanism (24) may include a swivel collet or rotating grip.The first two positions allow comfortable control of the tool withoutstraining a user's arm, wrist, or fingers. And the third reduces thereach and awkward postures that many users, such as surgeons, encounterwhile performing their tasks, especially from a reverse position.

Referring next to FIG. 3, there are six controls located on the toolhandle (12) including a squeeze grip (20), slip lock trigger (22), acollet mechanism (24), a control sphere (26), and sphere lock (28). Inone embodiment, the controls are placed so they are reachable by thethumb or index finger. However, it will be appreciate that the toolhandle (12) may be used in a variety of ways such that the controls canbe reached by other fingers.

The squeeze grip (20) actuates the graspers (18) at the end of the tool(10). When the grip (20) is squeezed closed, the graspers (18) close(the closed position is shown in FIG. 2). The grip (20) is sprung suchthat when released the graspers (18) will open if the slip lock isdisengaged (the open position is shown in FIG. 3). In one embodiment,the grip pivots (46) are located toward the distal end of the handlesuch that the stronger, more dexterous index and middle fingers cansqueeze the grip in some of the grip positions. In one embodiment, thepivot angle between the body of the handle and the squeeze grip (20)when the squeeze grip is open is about 4-18 degrees, preferably about 17degrees and the pivot angle when the squeeze grip is closed is about 0degrees.

With reference to FIGS. 4 and 5, in one embodiment, when the squeezegrip (20) is closed (as shown in FIG. 2), a slip lock (48) prevents thesqueeze grip (20) from opening. A ratcheting mechanism is used toperform this action. However, one of skill in the art will appreciatethat any variety of mechanisms or methods may be used to prevent thesqueeze grip (20) from opening. The slip lock (48) allows smooth motionwhile still preventing the squeeze grip (20) from reopening. The sliplock trigger (22) will disengage the slip lock (48), allowing thesqueeze grip (20) to open. The slip lock trigger (22) locks in positionwhen pulled back disengaging contact between the slip lock (48) andsqueeze grip (20). In one embodiment, the slip lock (48) is locatedabout 2-3 cm, preferable, about 2.7 cm, from the collet mechanism (24)and is substantially centered along the lateral axis of the handle (12).In this embodiment, the actuation force needed to for the sliplock (48)to rotate the shaft (14) is between about 0.5 and 1.0 lbs, preferablyabout 0.6 lbs.

With reference to FIG. 6, a collet mechanism (24) is located on thefront of the handle (12). When rotated, a collet mechanism (24) turnsthe end effector (16) about the axis of the tool shaft (14). The colletmechanism (24) is free to rotate 360 degrees. In one gripping position,the collet mechanism (24) is reached with the index finger forone-handed operation. However, depending on the grip position, thecollet mechanism (24) may be reached with a user's thumb or otherfinger.

With reference to FIGS. 1, 7 and 8, the control sphere (26) actuates thepitch and yaw of the end effector (16). The control sphere (26) can alsobe used to rotate to end effector (16) in the same manner as the colletmechanism (24). A small tactile element (50) on the top the sphere (26)aligns with the tool shaft (14) when the end effector (16) is alignedwith the shaft (14). The tactile element (50) provides a sense of touchfor location of the end effector (16). The tactile element (50) is aninward element or an outward bump to orient a user as to the position ofarticulation. Control is intuitive where moving the tactile element (50)forward/up (52) moves the tip of the end effector up (60), and movingthe tactile element (50) backward/down (54) moves the end effector down(62). Likewise, moving the tactile element (50) left (56) or right (58)moves the end effector left (64) or right (66), respectively.

In one embodiment, the control sphere is located in at or near thecenter of the lateral axis of the handle and about 3-4 cm from thecollet mechanism (24). In one embodiment, the control sphere is locatedabout 3.6 cm from the collet mechanism (24) and is substantially inlinewith the shaft (14). In this embodiment, the actuation force needed tomove the control sphere such that it moves the end effector properlybetween about 2 and 5 lbs, preferably about 3 lbs.

With reference to FIG. 4, the sphere lock (28) is an internal mechanisminvolving a wave spring (82). When in the released position, the wavespring (82) pushes the control sphere (26) into contact with the insideof the handle shell (68) which locks the sphere (26) in place which inturn prevents articulation of the end effector (16). Also, because thesphere (26) and collet mechanism (24) both rotate the shaft (14), thesphere lock (28) prevents rotation of the end effector (16) but allowsindependent rotation of the shaft while the end effector remains in thelocked position. When the control sphere (26) is depressed, the wavespring (82) is flattened and the control sphere (26) is released,leaving it free to move. The sphere lock (28) allows the articulatingend effector (16) to be placed in one position and the digit (thumb orfinger) removed from the sphere (26) which locks the articulation inplace. To move the articulating end effector (16), pressure from thedigits is required. Thus, the articulation is stationary once the sphere(26) is not under digital pressure and can move freely once unlocked,after the digit (thumb or finger) engages the control sphere (26).

With reference to FIG. 12, in one embodiment the actuating end effector(16) is based on a spherical shape. It will be appreciated that thearticulating end effector may take any shape, however. The spherical endeffector (16) may be of any size proportional to the graspers (18) andshaft (14). In one embodiment, the end effector (16) is approximatelyabout 10 mm in diameter, scaled to the size of the shaft (14). Attachedto the front of the spherical end effector (16) is a protrusion with twowings (36) that hold the graspers (18) via a pin (37). Small wings (36),similar to those found on the current rigid tools, are attached to thespherical end effector (16) to hold the graspers' (18) pivot point fromthe end effector's (16) center. A slot (38) between the wings (36) isalso used to allow grasper movement.

In one embodiment, a portion of the spherical end effector (16) isremoved leaving approximately ½-¾ of a sphere. However, it can beappreciated that different amounts of a spherical end effector may beremoved. A small hole (40) extends through the end effector to allow thegrasper cable to pass. In the embodiment having a spherical end effector(16) that is approximately about 10 mm in diameter, the small hole (40)is approximately about 2 mm in diameter. The spherical end effector (16)is split across the equator for attachment of control cables (42)described in more detail below. Four attachment mechanisms, such asscrews, hold the end effector (16) together and secure the controlcables (42) to the end effector (16).

With reference to FIG. 10, the pitch and yaw of the end effector (16)are actuated by the control sphere (26). In one embodiment, fourinextensible control cables (42) connect the control sphere through theshaft (14) to the end effector (16). It will be appreciated that thecontrol cables may be wires or the like and that any number of controlcables may be used to connect the control sphere (26) to the endeffector (16). The control cables are fed through four wire guides (44)internal to the shaft (14) to prevent end-effector (16) and controlsphere (26) from having shaft-independent rotation.

In one embodiment, the control sphere (26) is about three times largerthan the end effector (16). For example, if the spherical end effector(16) is about 10 mm in diameter, the control sphere (26) is about 30 mmdiameter. The difference in size enables the user to have more precisecontrol over the end effector (16). Also, in one embodiment, the controlsphere (26) is in-line with the actuating effector (16).

In one embodiment, the control cables (42) running through the shaft(14) are rotated a total of about 180° when passed through the wireguides (44). This rotation ensures that when the control sphere (26) ismoved left, the end effector (16) will move left, and when the controlsphere (26) is moved forward, the end effector (16) will move up.

The four control cables (42) have swaged balls attached to each end. Inthe embodiment with an end effector (16) having a diameter of about 10mm, the swaged balls and each end of the four control cables (42) areapproximately about 2 mm. Both the end effector and control sphere aresplit along their equators. The swaged ends of the control cables (42)seed into depressions (39) in each hemisphere of the end effector (16).Four attachment mechanisms, such as screws, hold the two hemispheres ofthe end effector (16) together and secure the control cables (42). Thecontrol cables (42) connect to the control sphere (26) also seed intodepressions (37) in the control sphere (26). One attachment mechanism,such as a screw, holds the top half of the control sphere (26) in placeand secures the control cables (42). A screw cover may be used to hidethe screw and has a small tactile element for tactile feedback.

The tool shaft (14) is able to rotate 360°. Normally, rotation of thecontrol ball would cause the control cables to become tangled;consequently, control of the end effector (16) would be lost. The tool(10) allows the shaft (14) and actuating end effector (16) (along withthe cables (42)) to rotate about the tool handle (12) without becomingentangled.

With continued reference to FIG. 10, the graspers (18) are opened andclosed by the movement of an actuator rod (70) located within shaft(14). The internal mechanism was designed to allow an external forwardand backward movement to control the graspers (18), while allowingrotation that does not twist or bind the internal control cables (42).The actuator rod (70) extends through the shaft (14) and wire guides(44). At the control sphere (26) end, two halves of a pull cylinder (72)are connected to the actuator rod (70) by two pins that extend throughthe actuator rod (70) perpendicular the axis of the actuator rod (70).The pull cylinder (72) is free to move forward and backward along theshaft (14). At the actuating end, a flexible cable (not shown) extendsfrom the shaft and connects to an eyelet that opens and closes thegraspers (18) when the actuator rod (70) moves forward and backward.When the pull cylinder (72) is moved back toward the control sphere(26), the graspers (18) close. When the pull cylinder (72) is pushedforward, the graspers (18) open.

With reference to FIG. 9, four-piece assembly of cylinder (72) allowsthe pull cylinder (72) to rotate with the shaft (14) while the outercovers (74) are stationary. A rotary cylinder (76) slides over the outercovers (74) such that the posts on the outer covers (74) feed throughinclined tracks on the rotary cylinder (76). When the rotary cylinder(76) is turned, the outer covers (74) are forced forward and backwardactuating the graspers (18). The control sphere (26) rests in a cradle(78) that has four ball bearings embedded in it for smooth operation.Extending from the bottom of the cradle (78) is a short shaft (notshown) that mates with the shaft (14) of the tool (10). This maintainsthe rotation of the control sphere (26) with the end effector (16) sothe control cables (42) do not become tangled. A TEFLON bearing (80)allows the cradle (78) to rotate smoothly with the shaft (14) and a wavespring (82) for the sphere lock (28).

With reference to FIG. 13, rotary cylinder (76) is connected to thesqueeze grip (20) by an actuating cable (not shown). It will beappreciated that the actuating cable may be any type of cable includinga pull cable and push-pull cable. The cable has two swaged ball endsthat fit into a protrusion (86) on the squeeze grip (20) and a recess onthe rotary cylinder (76). The cable runs through a groove (84) in theleft side of the handle (90). The squeeze grip (20) is spring-loadedsuch that the graspers (18) open when the squeeze grip (20) is released.

The handle (12) can comprise multiple components or may be onecomponent. In one embodiment, the handle (12) comprises a right half ofhandle (88), left half of handle (90) and a handle grip (90). One ofskill in the art will appreciate that the handle (12) may be made up ofany number of components or may be a unitary handle.

From the foregoing, it will be seen that this invention is one welladapted to attain all the ends and objects hereinabove set forthtogether with other advantages which are obvious and which are inherentin the structure. It will be understood that certain features andsubcombinations are of utility and may be employed without reference toother features and subcombinations. This is contemplated by and iswithin the scope of the claims. Since many possible embodiments may bemade of the invention without departing from the scope thereof, it is tobe understood that all matter herein set forth or shown in theaccompanying drawings is to be interpreted as illustrative and not in alimiting sense.

1. (canceled)
 2. An article of manufacture, comprising: an ergonomic handle comprising a plurality of controls, the handle comprising a body portion having a top surface, an opposite bottom surface, a proximal end, and a distal end, the top surface contoured to complement the natural curve of a user's palm; the plurality of controls comprising a squeeze grip, a control sphere, and a collet mechanism; and a plurality of shafts, each shaft having a proximal end and a distal end, wherein the proximal end of each shaft is interchangeably connectable with the distal end of the handle; wherein the distal end of each shaft comprises an end effector, wherein the end effector of each shaft comprises a different tool, wherein the tool is selected from the group consisting of graspers, cutting forceps, jaws, and an cauterizer; wherein, upon operably connection of the proximal end of one of the plurality of shafts to the distal end of the handle, the squeeze grip on the handle actuates the tool on the end effector; the control sphere actuates the pitch and yaw of the end effector; and the collet mechanism turns the end effector about the axis of the shaft.
 3. The article of manufacture of claim 2, wherein the handle is about 150-165 mm in length, about 30-40 mm in height, and about 40-50 mm in width.
 4. The article of manufacture of claim 2, wherein the handle is about 155 mm in length, about 35 mm in height, and about 45 mm in width.
 5. The article of manufacture of claim 2, wherein the handle has a circumference of about 4 to 6.5 cm.
 6. The article of manufacture of claim 2, wherein the handle has a circumference of about 5 cm.
 7. The article of manufacture of claim 2, wherein the distal end of the handle is curved such that the shaft, when operably connected to the handle, is angled at about 135 degrees relative to a longitudinal axis of the handle.
 8. The article of manufacture of claim 2, wherein the handle further comprises a slip lock, wherein the slip lock locks the squeeze grip in a closed position to prevent it from opening.
 9. The article of manufacture of claim 8, wherein the handle further comprises a slip lock trigger to disengage the slip lock.
 10. The article of manufacture of claim 2, wherein the handle further comprises a rotatable knob.
 11. The article of manufacture of claim 10, wherein the rotatable knob drives rotation of the shaft relative to the handle.
 12. The article of manufacture of claim 2, wherein the handle further comprises a control sphere lock, wherein the control sphere lock locks the control sphere into place, preventing articulation of the end effector.
 13. The article of manufacture of claim 2, wherein the shaft is about 3 mm to about 10 mm in diameter.
 14. The article of manufacture of claim 2, wherein the shaft is about 3 mm in diameter.
 15. The article of manufacture of claim 2, wherein the shaft is about 5 mm in diameter.
 16. The article of manufacture of claim 2, wherein the shaft is about 10 mm in diameter.
 17. The article of manufacture of claim 2, wherein the shaft is about 35 cm to about 55 cm in length.
 18. The article of manufacture of claim 2, wherein the shaft is about 40 cm in length.
 19. The article of manufacture of claim 2, wherein the shaft, when operably connected to the handle, is angled at about 135 degrees relative to a longitudinal axis of the handle.
 20. The article of manufacture of claim 2, wherein the end effector is powered.
 21. The article of manufacture of claim 2, wherein the end effector is spherically shaped.
 22. The article of manufacture of claim 21, wherein the end effector is about 10 mm in diameter.
 23. The article of manufacture of claim 21, wherein the end effector is about 10 mm in diameter and the control sphere is about 30 mm in diameter.
 24. The article of manufacture of claim 21, wherein the diameter of the control sphere is about three times larger than the diameter of the spherical surface of the end effector.
 25. The article of manufacture of claim 2, wherein the control sphere comprises a tactile element.
 26. The article of manufacture of claim 2, wherein the tactile element aligns the control sphere with the shaft.
 27. The article of manufacture of claim 2, wherein the control sphere is located at or near the center of a lateral axis of the handle and substantially inline with the shaft.
 28. The article of manufacture of claim 2, wherein the control sphere is located in the handle at a position that is substantially inline with the end effector.
 29. The article of manufacture of claim 2, wherein the control sphere rotates the shaft.
 30. The article of manufacture of claim 2, wherein the control sphere and the end effector rotate with the shaft.
 31. The article of manufacture of claim 2, wherein the squeeze grip is movably arranged on the bottom surface of the handle.
 32. The article of manufacture of claim 2, wherein the squeeze grip has a pivot point located toward the distal end of the handle.
 33. The article of manufacture of claim 2, wherein the squeeze grip is open about 4 to 18 degrees from the bottom surface of the handle when it is not actuated by a user, and wherein the squeeze grip is open about 0 degrees from the bottom surface of the handle when actuated by a user.
 34. The article of manufacture of claim 2, wherein the control sphere is arranged along the top surface of the handle such that the control sphere is accessible to a user's thumb while the user grips the squeeze grip lever projecting from the bottom surface of the handle.
 35. The article of manufacture of claim 2, wherein the pitch of the end effector is moved up when the control sphere is moved up, wherein the pitch of the end effector is moved down when the control sphere is moved down, wherein the yaw of the end effector is moved left when the control sphere is moved left, wherein the yaw of the end effector is moved right when the control sphere is moved right.
 36. The article of manufacture of claim 2, wherein the pitch of the end effector is moved up when the control sphere is moved down, wherein the pitch of the end effector is moved down when the control sphere is moved up, wherein the yaw of the end effector is moved left when the control sphere is moved right, wherein the yaw of the end effector is moved right when the control sphere is moved left. 